<ui:composition template="/template.xhtml" 
                xmlns="http://www.w3.org/1999/xhtml"
                xmlns:ui="http://java.sun.com/jsf/facelets">
    <ui:define name="body">
        <div class="mastbod">
            Erreur !!!
            <hr style="clear: both; visibility: hidden;" />
        </div>
    </ui:define>
</ui:composition>